Analyses of Books. 623 
. ^. e here an analysis of the water of Lake Superior, which 
is of remarkable purity. The total weight of solid matter in 
solution is only 2-66 grains per gallon, no organic matter being 
mentioned as present, though it is added that the permanganate 
test showed 0-35 part of oxygen consumed by organic matter 
pei million parts of water. The hardness is only 3^3 degrees, 
and phosphates are absent. 
Judging from the three parts before us, Natural History plays 
no important part in the Survey. We find no account of the 
flora of Minnesota, and in Zoology there are merely three papers 
on Crustacea, — viz., the Cyclopidae of Minnesota, with notes on 
other Copepoda ; the Cladocera of Minnesota ; and on Notodro- 
mas and Cambarus. 
In the Tenth Report there is complaint concerning the fre- 
quency and destructive character of forest fires. Special legis- 
lation is recommended, and joint aCtion with the Dominion 
Government is suggested, since the fires begin on both sides of 
the boundary. 
Facts proving that Lightning is a Composite Force. By W. 
Boggett. London : Ridgway. 
In this pamphlet the author adheres to a view which he has ex- 
pressed in a former publication, viz., that water does not consist 
of oxygen and hydrogen alone, but likewise of electricity. This 
hypothesis seems to us to involve the materiality of electricity 
He does not, however, say that he has experimentally proved 
this proposition. He says — “ Some few, indeed, have been told 
that it is composed of two explosive gases, but very few trouble 
themselves to ask how such gases (if water contained nothing 
else) could possibly extinguish fires, or how they came to be 
fluid.” Now water is not composed of two explosive gases ; 
neither oxygen nor hydrogen is, per se, explosive. If a light is 
applied to them when mixed they burn with an explosion. 
The author does not show how or why the presence of electri- 
city as a constituent should enable water to extinguish fires, or 
render it fluid. He tells us that Faraday proved that ice is a 
non-conduCtor of electricity. Dry ice is certainly a very bad 
conductor, though there are not a few substances which conduCt 
electricity still worse. But when melting it conducts better than 
water. Mr. Boggett is exercised by the fa Cl that water when 
freezing exerts great force if confined, — that is, in a vessel which 
gives no room for expansion. But what objection can he make 
to the common explanation that water in freezing assumes a 
crystalline form, and being thus expanded becomes specifically 
lighter, — just as solid tin floats upon melted tin ? But there 
